This invention relates in a general aspect to plas in which at least one polymer layer in direct contact with the metallic substrate (a) comprises a random copolymer of ethylene and an ethylenically unsaturated carboxylic acid and (b) bears on its surface opposite said metallic substrate a layer of a blend of either the same or a different random ethylene/ethylenically unsaturated carboxylic acid copolymer and at least one olefin polymer resin which is not a random ethylene/ethylenically unsaturated carboxylic acid copolymer and (II) to cable shielding and/or armoring tapes and electrical communications cables prepared from such laminates.
In the manufacture and use of various laminated or composite articles involving one or more metallic layers or substrates having one or more layers or coatings of a thermoplastic polymer material adhered thereto, an oftentimes controlling factor or consideration governing their suitability for various end-use applications is the degree of adhesion as between the various polymeric and metallic layers in such laminated or composite articles. A particular example of an area in which the adhesion between the various layers in a plastic/metal composite article is of great concern can be found in U.S. Pat. No. 4,132,857 wherein the need for improved adhesion as between the polyethylene insulation jacketing material and the metal sheath in electrical cable constructions is discussed. More specifically, such patent proposes to improve the adhesion between said polyethylene jacketing material and said metal sheath by using, in place of the more conventionally employed ethylene/acrylic or methacrylic acid copolymer adhesive layer, a coextruded dual film laminate comprising (1) a first film that the above-discussed approach of U.S. Pat. No. 4,132,857 may be capable of providing some measure of improved jacketing resin adhesion in certain instances when measured at room temperature, such an improvement in room temperature adhesion performance does not appear to be consistently achieved across the full range of possible jacketing resin/second film layer combinations. (See, for example, the data summarized in the hereinafter presented working examples.) Moreover, it has also been found that even when good room temperature jacketing resin adhesion is obtained (e.g., either by the above-discussed dual film layer approach of U.S. Pat. No. 4,132,857 or via a monolayer ethylene/acrylic or methyacrylic acid copolymer-coated metal shielding tape approach), such adhesion value can often times be dramatically less when measured at high and/or low adhesion testing temperatures.
In view of the fact that various plastic/metal composite articles or laminates can reasonably be expected to be installed and/or otherwise used (e.g., as electrical communications cables; as metal/plastic/metal laminates for potential use as electrical appliance housings, in heating ducts, in various automotive applications, etc.) at temperatures substantially above or below normal room temperature (e.g., 20.degree.-25.degree. C.), it would be highly desirable to provide a means of improving the high and/or low temperature adhesion as between metal substrates and olefin polymer outer coating or inner core layers in such plastic/metal composite articles or laminates.